// -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
/*
 *  Copyright 2008 ZXing authors All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <zxing/qrcode/detector/AlignmentPatternFinder.h>
#include <zxing/ReaderException.h>
#include <zxing/common/BitArray.h>
#include <vector>
#include <cmath>
#include <cstdlib>

using std::abs;
using std::vector;
using zxing::Ref;
using zxing::qrcode::AlignmentPatternFinder;
using zxing::qrcode::AlignmentPattern;

// VC++

using zxing::BitMatrix;
using zxing::ResultPointCallback;

float AlignmentPatternFinder::centerFromEnd(vector<int> &stateCount, int end) {
    return (float) (end - stateCount[2]) - stateCount[1] / 2.0f;
}

bool AlignmentPatternFinder::foundPatternCross(vector<int> &stateCount) {
    float maxVariance = moduleSize_ / 2.0f;
    for (int i = 0; i < 3; i++) {
        if (abs(moduleSize_ - stateCount[i]) >= maxVariance) {
            return false;
        }
    }
    return true;
}

float AlignmentPatternFinder::crossCheckVertical(int startI, int centerJ, int maxCount,
                                                 int originalStateCountTotal) {
    int maxI = image_->getHeight();
    vector<int> stateCount(3, 0);


    // Start counting up from center
    int i = startI;
    while (i >= 0 && image_->get(centerJ, i) && stateCount[1] <= maxCount) {
        stateCount[1]++;
        i--;
    }
    // If already too many modules in this state or ran off the edge:
    if (i < 0 || stateCount[1] > maxCount) {
        return nan();
    }
    while (i >= 0 && !image_->get(centerJ, i) && stateCount[0] <= maxCount) {
        stateCount[0]++;
        i--;
    }
    if (stateCount[0] > maxCount) {
        return nan();
    }

    // Now also count down from center
    i = startI + 1;
    while (i < maxI && image_->get(centerJ, i) && stateCount[1] <= maxCount) {
        stateCount[1]++;
        i++;
    }
    if (i == maxI || stateCount[1] > maxCount) {
        return nan();
    }
    while (i < maxI && !image_->get(centerJ, i) && stateCount[2] <= maxCount) {
        stateCount[2]++;
        i++;
    }
    if (stateCount[2] > maxCount) {
        return nan();
    }

    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
    if (5 * abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
        return nan();
    }

    return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : nan();
}

Ref<AlignmentPattern> AlignmentPatternFinder::handlePossibleCenter(vector<int> &stateCount, int i,
                                                                   int j) {
    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
    float centerJ = centerFromEnd(stateCount, j);
    float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1], stateCountTotal);
    if (!isnan(centerI)) {
        float estimatedModuleSize = (float) (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
        int max = possibleCenters_->size();
        for (int index = 0; index < max; index++) {
            Ref<AlignmentPattern> center((*possibleCenters_)[index]);
            // Look for about the same center and module size:
            if (center->aboutEquals(estimatedModuleSize, centerI, centerJ)) {
                return center->combineEstimate(centerI, centerJ, estimatedModuleSize);
            }
        }
        AlignmentPattern *tmp = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
        // Hadn't found this before; save it
        tmp->retain();
        possibleCenters_->push_back(tmp);
        if (callback_ != 0) {
            callback_->foundPossibleResultPoint(*tmp);
        }
    }
    Ref<AlignmentPattern> result;
    return result;
}

AlignmentPatternFinder::AlignmentPatternFinder(Ref<BitMatrix> image, int startX, int startY,
                                               int width,
                                               int height, float moduleSize,
                                               Ref<ResultPointCallback> const &callback) :
        image_(image), possibleCenters_(new vector<AlignmentPattern *>()), startX_(startX),
        startY_(startY),
        width_(width), height_(height), moduleSize_(moduleSize), callback_(callback) {
}

AlignmentPatternFinder::~AlignmentPatternFinder() {
    for (int i = 0; i < int(possibleCenters_->size()); i++) {
        (*possibleCenters_)[i]->release();
        (*possibleCenters_)[i] = 0;
    }
    delete possibleCenters_;
}

Ref<AlignmentPattern> AlignmentPatternFinder::find() {
    int maxJ = startX_ + width_;
    int middleI = startY_ + (height_ >> 1);
    //      Ref<BitArray> luminanceRow(new BitArray(width_));
    // We are looking for black/white/black modules in 1:1:1 ratio;
    // this tracks the number of black/white/black modules seen so far
    vector<int> stateCount(3, 0);
    for (int iGen = 0; iGen < height_; iGen++) {
        // Search from middle outwards
        int i = middleI + ((iGen & 0x01) == 0 ? ((iGen + 1) >> 1) : -((iGen + 1) >> 1));
        //        image_->getBlackRow(i, luminanceRow, startX_, width_);
        stateCount[0] = 0;
        stateCount[1] = 0;
        stateCount[2] = 0;
        int j = startX_;
        // Burn off leading white pixels before anything else; if we start in the middle of
        // a white run, it doesn't make sense to count its length, since we don't know if the
        // white run continued to the left of the start point
        while (j < maxJ && !image_->get(j, i)) {
            j++;
        }
        int currentState = 0;
        while (j < maxJ) {
            if (image_->get(j, i)) {
                // Black pixel
                if (currentState == 1) { // Counting black pixels
                    stateCount[currentState]++;
                } else { // Counting white pixels
                    if (currentState == 2) { // A winner?
                        if (foundPatternCross(stateCount)) { // Yes
                            Ref<AlignmentPattern> confirmed(handlePossibleCenter(stateCount, i, j));
                            if (confirmed != 0) {
                                return confirmed;
                            }
                        }
                        stateCount[0] = stateCount[2];
                        stateCount[1] = 1;
                        stateCount[2] = 0;
                        currentState = 1;
                    } else {
                        stateCount[++currentState]++;
                    }
                }
            } else { // White pixel
                if (currentState == 1) { // Counting black pixels
                    currentState++;
                }
                stateCount[currentState]++;
            }
            j++;
        }
        if (foundPatternCross(stateCount)) {
            Ref<AlignmentPattern> confirmed(handlePossibleCenter(stateCount, i, maxJ));
            if (confirmed != 0) {
                return confirmed;
            }
        }

    }

    // Hmm, nothing we saw was observed and confirmed twice. If we had
    // any guess at all, return it.
    if (possibleCenters_->size() > 0) {
        Ref<AlignmentPattern> center((*possibleCenters_)[0]);
        return center;
    }

    throw zxing::ReaderException("Could not find alignment pattern");
}
